Management of data transaction from I/O devices

ABSTRACT

Embodiments include a technique for management of data transactions, where the technique includes receiving, at a link interface, a packet from an I/O device, wherein the packet includes address information, and performing, by a host bridge, an address translation for the address information included in the packet. The technique also includes responsive to performing the address translation, determining a target page associated with a translated address of the packet is for at least one of a payload target page or a signaling target page, and appending a flag to a command based at least in part on the target page being associated with the translated address of the packet. The technique includes transmitting the command to an ordering controller for ordering the packet.

BACKGROUND

The present invention generally relates to data management, and morespecifically, to the management of data transactions from I/O devices.

I/O devices are used in computer and mainframe systems for storing andtransferring data. Mainframes and computing systems can process highvolumes of I/O data and are configured to simultaneously supportapplications and I/O devices to service thousands of users. Directmemory access (DMA) can be used by various hardware including disk drivecontrollers, graphics cards, network cards, sound cards, etc. ofcomputer systems to transfer data between devices with less CPUoverhead. DMA can also be used in intra-chip data transfer in multi-coreprocessors without occupying the CPU time.

When using DMA, the CPU first initiates the transfer, and then the CPUis made available to perform other operations while the initial transferof data into the memory is in progress. This allows the CPU to performother useful work or priority tasks while waiting for relatively slowI/O data transfers to be completed. This is also useful at any time theCPU cannot keep up with the rate of a data transfer. As thefunctionality and capacity of mainframes continue to grow, themanagement of the data, in particular I/O data, should be efficientlyprocessed to limit any delays experienced by the system.

SUMMARY

Embodiments of the present invention are directed to acomputer-implemented method for management of data transactions from I/Odevices. A non-limiting example of the computer-implemented methodincludes receiving, via a link interface, a packet from an I/O device,wherein the packet includes address information, and performing, via ahost bridge, an address translation for the address information includedin the packet. The computer-implemented method also includes responsiveto performing the address translation, determining a target pageassociated with a translated address of the packet is for at least oneof a payload target page or a signaling target page, and appending aflag to a command based at least in part on the target page beingassociated with the translated address of the packet. The computerimplemented method includes transmitting the command to an orderingcontroller for ordering the packet.

Embodiments of the present invention are directed to a system formanagement of data transactions from I/O devices. A non-limiting exampleof the system includes one or more processors and at least one memory,where the memory includes instructions that are executable by at leastone of the one or more processors. The one or more processors areconfigured to receive, via a link interface, a packet from an I/Odevice, wherein the packet includes address information, and perform anaddress translation for the address information included in the packet.The one or more processors are further configured to responsive toperforming the address translation, determine a target page associatedwith a translated address of the packet is for at least one of a payloadtarget page or a signaling target page, append a flag to a command basedat least in part on the target page associated with the translatedaddress of the packet. The one or more processors are configured totransmit the command to an ordering controller for processing thepacket.

Embodiments of the invention are directed to a computer program productfor management of data transactions, the computer program productcomprising a computer readable storage medium having programinstructions embodied therewith. The program instructions are executableby a processor to cause the processor to receive a packet from an I/Odevice, wherein the packet includes address information, and perform anaddress translation for the address information included in the packet.The instructions are further executable to cause the processor toresponsive to performing the address translation, determine a targetpage associated with a translated address of the packet is for at leastone of a payload target page and a signaling target page, and append aflag to a command based at least in part on the target page associatedwith the translated address of the packet. The instructions are furtherexecutable to cause the processor to transmit the command to an orderingcontroller for processing the packet.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments of the invention are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 depicts a block diagram illustrating one example of a processingsystem for practice of the teachings herein;

FIG. 2 depicts block diagram of a system in accordance with anembodiment for management of data transactions from I/O devices;

FIG. 3 depicts a flow chart of a method for management of datatransactions from I/O devices in accordance with an embodiment; and

FIG. 4 depicts a flow chart of a method for management of datatransactions from I/O devices in accordance with an embodiment.

The diagrams depicted herein are illustrative. There can be manyvariations to the diagram or the operations described therein withoutdeparting from the spirit of the invention. For instance, the actionscan be performed in a differing order or actions can be added, deletedor modified. Also, the term “coupled” and variations thereof describeshaving a communications path between two elements and does not imply adirect connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification.

In the accompanying figures and following detailed description of thedisclosed embodiments, the various elements illustrated in the figuresare provided with two or three digit reference numbers. With minorexceptions, the leftmost digit(s) of each reference number correspond tothe figure in which its element is first illustrated.

DETAILED DESCRIPTION

Various embodiments of the invention are described herein with referenceto the related drawings. Alternative embodiments of the invention can bedevised without departing from the scope of this invention. Variousconnections and positional relationships (e.g., over, below, adjacent,etc.) are set forth between elements in the following description and inthe drawings. These connections and/or positional relationships, unlessspecified otherwise, can be direct or indirect, and the presentinvention is not intended to be limiting in this respect. Accordingly, acoupling of entities can refer to either a direct or an indirectcoupling, and a positional relationship between entities can be a director indirect positional relationship. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein.

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” may be understood to include any integer numbergreater than or equal to one, i.e. one, two, three, four, etc. The terms“a plurality” may be understood to include any integer number greaterthan or equal to two, i.e. two, three, four, five, etc. The term“connection” may include both an indirect “connection” and a direct“connection.”

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

For the sake of brevity, conventional techniques related to making andusing aspects of the invention may or may not be described in detailherein. In particular, various aspects of computing systems and specificcomputer programs to implement the various technical features describedherein are well known. Accordingly, in the interest of brevity, manyconventional implementation details are only mentioned briefly herein orare omitted entirely without providing the well-known system and/orprocess details.

In computer systems, microprocessors operate on data stored in the mainmemory. Since there are capacity limitations on the main memory,additional storage devices, such as hard disks, are provided tosupplement the main memory. When the microprocessor performs anoperation the data is moved from the additional memory device into themain memory. Depending on the amount of data to be processed, thetransfer of data from the additional memory device to the main memorycan be a very time consuming process and can further delay theprocessing of other critical tasks. When the microprocessor is requiredto manage the transfer of data, the performance of the computer systemcan be impacted.

In an effort to assist the microprocessors from controlling all of datatransfers within a computer system between storage devices and the mainmemory, a direct memory access (DMA) controller can be used. The DMAcontroller receives information from the microprocessor indicating thelocation of the data to be transferred, the address associated with thedestination of the data, and the number of bytes of data to transfer.After the microprocessor has been programmed, the DMA controlleroversees the transfer of the memory data inside the computer systeminstead of the microprocessor. In one or more embodiments, DMAoperations are used to move data between input/output (I/O) devices andmemory.

In one scenario, DMA write requests entering the host are executed instrict order. For each DMA write operation, it can never be observedthat the store has arrived before one of its predecessors. Thereforehost processors are tasked with sequencing the packets of the receiveddata stream prior to a CPU performing an action on the data. Therequirement to order all payload stores can lead to a throughputdegradation and latency increase (up to 50% and more), compared to anunordered execution of payload stores.

Some processes running on a processor require the full ordering ofpackets of a data stream prior to processing. However, as packets areeither ordered when they are received or are ordered after beingreceived, a period of time is required for performing the sequencing ofthe packets. In addition, the complete ordering of packets may beunnecessary as all processes do not require the complete ordering of thepackets causing an ordering or sequencing controller to devote time toordering packets that are not required to be ordered by the receivingprocess. For example, some processes do not require payload data to besequenced when an interrupt signal or an indication is provided to aprocessor. The processor only requires that each piece of payload datais present and stored in the memory. However, in some instances,signaling information is required to be strictly ordered. Whenprocessing the signaling information, the previously received payloaddata can be pushed out prior to processing the signaling information.

Given the high volume of I/O data processed by mainframes, the effectsof a delay can quickly accumulate and add unnecessary processing delayto the system when processing the plurality of transactions. Instead ofefficiently processing data, the CPU is held waiting for data transfersto the CPU memory to be completed. In one or more examples, the delaycan be attributed to the sequencing of data that does not requiresequencing. The full ordering of the incoming data stream comes at ahigh cost in terms of latency and throughput limitations. Each piece ofdata that is to be written to a memory subsystem does not require aparticular sequence, therefore, sequencing this particular data adds tothe latency, processing delay, and reduces the bandwidth of the system.

Although I/O devices can indicate whether data requires strictsequencing, the external I/O devices along the transfer path may not bereliable as different vendors of the external devices can manage andmark the I/O data streams using different techniques. The orderingcontroller will then be required to have knowledge of “how” each of theexternal devices in the I/O path from the source to the destinationdevice manages the data. In addition, the full ordering of a data streamincreases the latency and throughput limitations of processing,potentially causing the CPU to wait an unnecessary period of time duringprocessing as a single process is holds up the processing as data isbeing transferred to the memory.

Turning now to an overview of the aspects of the invention, one or moreembodiments of the invention address the above-described shortcomings ofthe prior art by providing a technique to reliably determine whichpackets are associated with signaling target pages and payload targetpages based on information provided in an address translation table. Anoperating system O/S can provide the context information for thesignaling and payload data, and firmware/software can annotate anaddress translation table to determine whether the strict ordering isrequired for the data.

The described techniques perform the internal classification andgenerating a flag based on context information provided by a program,such as an O/S, where the program has knowledge of the locations in thememory subsystem. In a different embodiment, the program can also be adriver or an application. This is distinguished from receiving a packetthat has been marked or flagged by an external device that may haveprocessed, received, and/or forwarded the packet.

The above-described aspects of the invention address the shortcomings ofthe prior art by having a program running on a processor classify theI/O data of the data stream as either signaling or payload data based onthe targeted page associated with the I/O data. As a result, theordering controller can relax the ordering based on the classificationto increase the CPU processing efficiency and bandwidth.

In one or more embodiments, the firmware/software allocates a page for adata transfer, where the firmware/software is aware of whether the pagewill contain either payload data or signaling information. In the eventthe page is associated with a payload operation, the firmware/softwaresets a payload ordering hint bit in an address translation entry of anaddress translation table. When the host bridge performs a fetchoperation in the address translation entry, the host bridge will look atthe payload ordering hint bit. In addition to performing the addresstranslation, the host bridge will forward this hint indication for eachdata store into that page.

Next, an ordering controller of the PCI-Express bridge controller (PBC)can use the ordering hint bit to order the data. In the event theordering hint bit is set, the PBC can relax the ordering for the DMAwrite operations resulting in the DMAs being unordered.

In the event the ordering hint bit is not set, for example signalingstores, the preceding payload stores can be pushed out of the memory.Signaling stores do not have the ordering hint bit set because signalingrequires strict ordering.

The techniques described herein are focused on extending the relaxationof the ordering of I/O data by using a firmware/software specified hintbits in the I/O address translation table in contrast to the naturalhardware understanding of payloads. In one or more embodiments, the hintbit is forwarded from the host bridge in a command to the orderingcontroller.

Conventionally, packets from I/O devices do not include any indicationof whether the data is associated with signaling or payload data.However, the programs that are running on the processor have knowledgewhether the data is signaling or payload data because the program willalready know which memory location(s) is associated with payload andsignaling information.

The techniques described herein also overcome the challenge of relyingon markings from external devices to control the management of I/O datato sequence the incoming data stream and unnecessarily sequencing thepackets of the data stream that do not require sequencing. Because thecontext information is provided internally by a program running on theprocessor there is no ambiguity in determining whether the I/O datatargets a payload or signaling page.

Referring to FIG. 1, there is shown an embodiment of a processing system100 for implementing the teachings herein. In this embodiment, thesystem 100 has one or more central processing units (processors) 101 a,101 b, 101 c, etc. (collectively or generically referred to asprocessor(s) 101). In one embodiment, each processor 101 may include areduced instruction set computer (RISC) microprocessor. Processors 101are coupled to system memory 114 and various other components via asystem bus 113. Read only memory (ROM) 102 is coupled to the system bus113 and may include a basic input/output system (BIOS), which controlscertain basic functions of system 100.

FIG. 1 further depicts an input/output (I/O) adapter 107 and a networkadapter 106 coupled to the system bus 113. I/O adapter 107 may be asmall computer system interface (SCSI) adapter that communicates with ahard disk 103 and/or tape storage drive 105 or any other similarcomponent. I/O adapter 107, hard disk 103, and tape storage device 105are collectively referred to herein as mass storage 104. Operatingsystem 120 for execution on the processing system 100 may be stored inmass storage 104. A network adapter 106 interconnects bus 113 with anoutside network 116 enabling data processing system 100 to communicatewith other such systems. A screen (e.g., a display monitor) 115 isconnected to system bus 113 by display adaptor 112, which may include agraphics adapter to improve the performance of graphics intensiveapplications and a video controller. In one embodiment, adapters 107,106, and 112 may be connected to one or more I/O busses that areconnected to system bus 113 via an intermediate bus bridge (not shown).Suitable I/O buses for connecting peripheral devices such as hard diskcontrollers, network adapters, and graphics adapters typically includecommon protocols, such as the Peripheral Component Interconnect (PCI).Additional input/output devices are shown as connected to system bus 113via user interface adapter 108 and display adapter 112. A keyboard 109,mouse 110, and speaker 111 all interconnected to bus 113 via userinterface adapter 108, which may include, for example, a Super I/O chipintegrating multiple device adapters into a single integrated circuit.

In exemplary embodiments, the processing system 100 includes a graphicsprocessing unit 130. Graphics processing unit 130 is a specializedelectronic circuit designed to manipulate and alter memory to acceleratethe creation of images in a frame buffer intended for output to adisplay. In general, graphics processing unit 130 is very efficient atmanipulating computer graphics and image processing, and has a highlyparallel structure that makes it more effective than general-purposeCPUs for algorithms where processing of large blocks of data is done inparallel.

Thus, as configured in FIG. 1, the system 100 includes processingcapability in the form of processors 101, storage capability includingsystem memory 114 and mass storage 104, input means such as keyboard 109and mouse 110, and output capability including speaker 111 and display115. In one embodiment, a portion of system memory 114 and mass storage104 collectively store an operating system to coordinate the functionsof the various components shown in FIG. 1.

One or more embodiments improve over the prior art by no longer havingto rely on information provided in a packet received from an I/O devicefor ordering a data stream into memory. The bandwidth is furtherincreased because the ordering of payload data can be relaxed, where theindication of the payload and/or non-payload data is determined by theprogram running on the processor which has knowledge of the memorylocation of the data. The program can instruct the hardware how tomanage data received in a data stream.

In one or more embodiments, the processing efficiency of the CPU isincreased due to the relaxed ordering of the data stream. In addition,the CPU is not being held up as data is being transferred into thememory subsystem from the I/O subsystem. The reliability is increaseddue to the internal classification of packets that are associated withsignaling and payload data.

Now referring to FIG. 2, a block diagram of a system 200 for managing ofdata transactions from I/O devices is shown.

The system 200 includes a plurality of devices 202 configured totransferring data either directly or over a network. In one or moreembodiments, the devices 202 are peripheral component interconnectPCI-Express connected I/O devices. The bridge unit 204 can be coupled toone or more of the devices 202 that are transferring data. The bridgeunit 204 is configured to send commands to the bridge controller 210used to manage data transfers. In an embodiment, the bridge unit 204 canbe a PCI-Express bridge unit (PBU). The PBU as shown is configured toperform address translation for received data of a data stream havingaddress information. The address translation can be used to convert anexternal address to an address associated with a location in the memorysubsystem 208. The I/O address translation logic 206 can be located inthe bridge unit. Systems exist where I/O address translation logic islocated in a host bridge, where the I/O translation logic serves totranslate virtual I/O addresses received over the I/O bus into physicaladdresses in the memory subsystem. In another embodiment, the bridgeunit 204 can be a host bridge (ETU) that performs the addresstranslation for the PCI-Express address. The ETU searches the memory anddetermines the target page associated with the PCI-Express address ofthe data packet. In one or more embodiments, the target page can eitherbe associated with a signaling page or a payload page. The ETU uses thisinformation and passes this information to the PCI-Express bridgecontroller which includes an ordering controller which controls theordering of the packets prior to transferring the packets to memorybased on the information from the ETU.

In an embodiment, the bridge controller 210 is a PCI-Express bridgecontroller (PBC). The PBC can include an ordering controller that isconfigured to communicate with the bridge unit 204, processor 212, andmemory subsystem 208. In one or more embodiments, processor 212 executesinstructions from program 214. The PCI-Express bridge controller usesthe information in the command to control the ordering of the packets tobe transferred to the memory. However, when a packet that is associatedwith signaling information is processed, the preceding packets will bepushed out regardless of having a flag set indicating the ordering hintbit or not.

In one or more embodiments, the ordering controller is a component ofthe PCI-Express bridge controller (PBC) that manages the received datathat is to be transferred to memory. In an embodiment, a bridge unit 204is configured to transmit commands to an ordering controller and theordering controller processes the data based on commands received fromthe bridge unit 204. In one or more embodiments, the bridge unit 204 isconfigured to modify the command message transmitted to the orderingcontroller of the PBC by appending a flag indicating whether a receivedpacket is associated with signaling or payload data. Responsive toreceiving the command, the PBC can control the transfer of data based atleast in part on the received command.

The bridge controller 210 as shown is coupled to the system memory 208.In one or more embodiments, the memory controller is a PCI-Expressbridge controller. The ordering controller is also coupled to theprocessor 212. An interrupt can be generated when I/O completionoperations are performed. In a different embodiment, a location inmemory can be polled to look for an indication indicating the I/O datahas been transferred to the memory and is ready for processing.

Now referring to FIG. 3, a method 300 for the management of datatransactions from I/O devices in accordance with an embodiment is shown.

Block 302 provides receiving, via a link interface, a packet from an I/Odevice, wherein the packet includes address information. The interfaceserves as a translator between the device and a program (O/S) on acomputing device. In one or more embodiments, the link interface can bea PCI-Express interface that receives data from an I/O device. In one ormore embodiments, the address information included in the packet is aPCI-Express address associated with respective PCI-Express devices.

Block 304 provides performing, via a host bridge, an address translationfor the address information included in the packet. In one or moreembodiments, the address information is translated to a physical addressof a memory location of the memory subsystem. The PCI-Express addressesare converted because external devices may not have any knowledge of thephysical addresses associated with the memory locations of the memorysubsystem.

Block 306 provides responsive to performing the address translation,determining a target page associated with a translated address of thepacket is for at least one of a payload target page and a signalingtarget page. A page is a data structure used by a computer system tostore mappings between virtual addresses and physical addresses. Virtualaddresses are used by the accessing process, while physical addressesare used by the hardware, or more specifically, by the RAM subsystem. Asa non-limiting example, virtual addresses can include the PCI-Expressaddresses of the devices. In one or more embodiments, an O/S running ona processor is responsible for mapping the virtual address provided bythe process to the physical address of the actual memory where the datais stored. In an embodiment, a page can be used to store signalinginformation while a different page can be used to store payloadsignaling.

Block 308 provides appending a flag to a command based at least in parton the target page associated with the translated address of the packet.In one or more embodiments, the host bridge (ETU) adds a flag to acommand that is transmitted to the ordering controller (of the PBC)indicating whether the packet is required to be ordered.

Block 310 provides transmitting the command to an ordering controller.In one or more embodiments, the ordering controller is a component ofthe PCI-Express bridge controller and transfers the packets inaccordance with the indication provided in the command.

Referring to FIG. 4, a different method 400 for the management oftransaction I/O data is shown. Block 402 provides receiving, via theordering controller, the command. In one or more embodiments, a PBCincludes an ordering controller that controls the transfer of data tothe memory.

Block 404 provides responsive to the flag being set, ignoring anordering of the payload data when writing the payload date into memory.In one or more embodiments, the ordering of payload packets does notrequire a strict sequencing. The I/O data which is payload data can betransferred to the memory in any order by the controller.

Block 406 provides responsive to the flag not being set, pushing out allpreceding payload data, regardless of previously received payload datahaving the flag set. Block 408 includes providing an indication to a CPUindicating the data is ready for processing.

The techniques described herein are focused on extending the orderingrelaxation of data in an I/O data stream by using firmware/softwarespecified hints in the I/O address translation table. In one or moreembodiments, the PBC maintains an ordering matrix having a size of N×M,where N is the number of stores that can be active in the PBC at a givenmoment. If a bit is set in row M of column N means that the store finitestate machine (FSM) N has an ordering dependency towards FSM M (meaningthat N has to be ordered behind M).

In addition, the PBC maintains a table with depth N, where each bitindicates, whether FSM indicates FSM N is busy with an active orderedcommand. When a command is received (in I/O mode) and the unordered bitis set, neither the ordering matrix nor the active ordered commandtables are updated.

When a command is received for FSM N and the unordered bit is not setfor I/O, the active ordered command table is copied into column N of theordering matrix and the bit N in the active ordered command matrix isset.

When a command M is completed, the row M in the ordering matrix is resetas well as the bit M in the active ordered command table. For couplingoperations, the unordered bit can be changed in semantics to set thecorresponding bit in the active ordered command table while not settingany bits in the corresponding row in the ordering matrix.

In one or more embodiments, an additional hint bit in addition to the“unordered” bit is used. The “relax ordering” bit can take the semanticsof the modified “unordered” behavior for coupling traffic. The DMAs withthe “relax ordering” bit will not wait for any predecessor, butsubsequent DMAs that do not have the “relax ordering” bit set will beordered behind even those with the “relax ordering” bit set. In one ormore embodiments, the “relax ordering” bit is set by the host bridge(ETU) when it forwards the command to the ordering controller in thePBC.

The ETU originates this bit from the I/O address translation entryassociated with a DMA. The ETU is configured to set the “relax ordering”bit based on the information of an I/O Address Translation Entryassociated with the DMA. Each I/O address translation entry has a bitindicating whether the DMA should have the “relaxed ordering” bit set.

In one or more embodiments, the firmware/software will set the “relaxordering” bit for each page that is associated with a payload transfer.The firmware/software will not set the “relax ordering” bit for thosepages that are targeted for signaling operations. Interrupts will pushout all DMA writes, regardless of the “relax ordering” bit being set.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instruction by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdescribed herein.

What is claimed is:
 1. A system for management of data transactions fromI/O devices, comprising: one or more processors; and at least onememory, the memory including instructions that, upon execution by atleast one of the one or more processors, wherein the one or moreprocessors are configured to: receive, via a link interface, a packetfrom an I/O device, wherein the packet includes address information;perform an address translation for the address information included inthe packet; responsive to performing the address translation, determinea target page associated with a translated address of the packet is forat least one of a payload target page or a signaling target page; appenda flag to a command based at least in part on the target page associatedwith the translated address of the packet; and transmit the command toan ordering controller for processing the packet; wherein the packetincludes at least one of a signaling or a payload data; responsive tothe flag being set, the one or processors are configured to ignore anordering of the payload data when writing the payload data into memory;and responsive to the flag not being set, pushing out all precedingpayload data, regardless of previously received payload data having theflag set.
 2. The system of claim 1, wherein the flag is set based on anordering hint bit of an address translation table being set by aprogram.
 3. The system of claim 2, wherein the program is one of anoperating system O/S, a driver, or an application.
 4. The system ofclaim 1, wherein the link interface is a peripheral componentinterconnect PCI-Express link interface, wherein the address informationof the packet is a PCI-Express address, and wherein the orderingcontroller is a PCI-Express bridge controller.
 5. The system of claim 4,wherein the address translation converts the PCI-Express address of thepacket to a memory location address of the memory.
 6. A computer programproduct for management of data transactions from I/O, the computerprogram product comprising: a computer readable storage medium havingstored thereon first program instructions executable by a processor tocause the processor to: receive a packet from an I/O device, wherein thepacket includes address information; perform an address translation forthe address information included in the packet; responsive to performingthe address translation, determine a target page associated with atranslated address of the packet is for at least one of a payload targetpage and a signaling target page; append a flag to a command based atleast in part on the target page associated with the translated addressof the packet; transmit the command to an ordering controller forprocessing the packet; wherein the packet includes at least one of asignaling or a payload data; responsive to the flag being set, ignore anordering of the payload data when writing the payload data into memory;and responsive to the flag not being set, pushing out all precedingpayload data, regardless of previously received payload data having theflag set.
 7. The computer program product of claim 6, wherein the flagis set based on an ordering hint bit of an address translation tablebeing set by a program.
 8. The computer program product of claim 6,wherein the packet is received at link interface, the link interfacebeing a peripheral component interconnect PCI-Express link interface,wherein the address information of the packet is a PCI-Express address,and wherein the ordering controller is a PCI-Express bridge controller.